Alteration of the mechanical properties of resins is often desired and improvement of the mechanical properties of epoxy resins by way of the addition of reactive butadiene-acrylonitrile copolymers has been extensively investigated. Improvements in flexural strength in such modified resins and in the toughness of carbon fiber composites made therefrom has been reported (See Gilwee et al., "Proceedings, National Symposium on Polymers in the Service of Man", Washington, D.C. (June 9-11, 1980)). Improvement in the fracture toughness of LARC-13, a high temperature addition polyimide adhesive, by use of an amine-terminated butadiene-acrylonitrile elastomer has also been reported (See St. Clair et al., "Proceedings, 12th National SAMPE Technical Conference", p. 729 (October 1980)). The preparation and characteristics of phosphorus-containing imide resins (See Varma et al., U.S. Pat. No. 4,276,344 and U.S. Pat. No. 4,395,557 and perfluoroethylene ether diamine (See Webster et al., Adv. in Chem. Series, No. 129, p. 61 (1973)) have been described. Further, the reaction of maleic acid imides with amines is also known (See Bargain et al., U.S. Pat. No. 3,562,223).
Even though improvements have been obtained in the nature of various resins by appropriate modifications as described in the prior art, it is desired to further improve the nature of and mechanical properties of resins.